In an electric vehicle or a hybrid electric vehicle, miniaturization or cost reduction of components to be mounted is important, a power converter converting a DC current of a battery into an AC current is not an exception and miniaturization or cost reduction thereof is being demanded. Accordingly, it is necessary to improve cooling performance because power density is increased as a result of this.
A power semiconductor module has the largest heat generation amount among electronic components configuring the power converter. In order to improve cooling performance of the power semiconductor module, a double-sided cooling structure (PTL 1) has been effective in which thermal grease having a large thermal resistance is removed and heat is radiated from both surfaces of a semiconductor device.
However, in the structure described in PTL 1, since the power semiconductor module and a flow path forming body are separately molded, it is necessary to provide a gap in addition to a flange section in consideration of assembling properties (particularly, between radiation fins and a wall surface of a flow path). Even if strict fitting tolerance is set and the gap is made small, due to a manufacturing variation of the power semiconductor module itself, there is a concern that interference by members may occur not in a sealing section. Particularly, if a plurality of power semiconductor modules are provided (a plurality of sealing sections are provided), it is not realistic to strictly regulate the fitting tolerance. Thus, if the power semiconductor module and the flow path forming body are separately molded, since there is certainly a finite gap with the variation and since cooling water flows through the gap in addition to a portion surrounding a heat radiation section to be flushed with cooling water in order to cool the power semiconductor module, there is a problem that cooling water bypasses heat radiation fins and cooling performance of the power semiconductor module cannot be sufficiently exhibited.